The first known fossil of a rare bloodsucker called the bat fly has been found in 20-million-year-old amber. What's more, the ancient bug was host to bat malaria, an even rarer find, according to a new study.

While there are hundreds of known bat fly species, most are poorly understood.

"First of all, it's hard to catch bats," Poinar said, "and [combing the bats for parasites is] like looking for fleas on mice. You don't see them."

Before Poinar discovered the amber containing the fossilized fly, nobody knew how recently the bugs had evolved to prey on bats alone. But even the 20-million-year-old fossil shows interesting bat-specific modifications, he said.

"The front legs are flattened, and they're held up between the head. These flattened legs kind of act as a plowshare, so as they are plowing along, they kind of part the hair of the bats so the [fly's] body can move all over the bat."

When Poinar examined the ancient fly under a microscope, he also found a new species of bat malaria, a parasitic disease so rare that perhaps five or six scientific papers have discussed it to date, he said.

The fossilized fly shows that bat malaria existed and was carried by bat flies as far back as 20 million years ago.

No Ancient Bats to Be Resurrected

Bat flies rarely leave their hosts, but they do roam in order to mate. This specimen was likely on the hunt for a partner when it got trapped in tree resin, which then fossilized to become amber.

Before he became a specialist in ancient diseases inside equally ancient bugs, Poinar had worked on attempting to extract DNA from insects trapped in amber—work which author Michael Crichton has acknowledged as part of his inspiration for Jurassic Park.

But no ancient bats will be reconstructed from this specimen, even if it were possible.

"As far as I'm concerned," Poinar said, "this specimen is so rare that we wouldn't want to attempt to try it."